The present disclosure relates to a polymer actuator, and more particularly to a polymer actuator which bends or deforms as a result of the migration of ions in response to the electric field applied.
An actuator made of an ion-conductive polymer (ion exchange resin) is drawing attention as a new actuator for its light weight and a large force produced thereby. In general, a polymer actuator has two electrode layers, one on each side of an ion-conductive polymer (ion exchange resin) film. The ion-conductive polymer contains water or other ion conducting medium and ions. In this polymer actuator, when a voltage is applied between the pair of electrodes, the ions migrate in the ion-conductive polymer layer, thus causing the same layer to bend or deform.
However, such a polymer actuator in the past using water as its ion conducting medium is no longer operational when it dries up as a result of the evaporation of water. Therefore, a polymer actuator using an ionic liquid has been proposed (see, for example, Japanese Patent Laid-Open No. 2007-143300, Japanese Patent Laid-Open No. 2007-329334, Japanese Patent Laid-Open No. 2008-86185, Japanese Patent Laid-Open No. 2008-251697, referred to as Patent Documents 1 to 4, respectively, hereinafter). Ionic liquid is a salt in a liquid state at room temperature and non-volatile. Using this liquid eliminates the need for water or other ion conducting medium, thus expanding the range of application of polymer actuators and providing improved reliability.
Further, the polymer actuators described in Patent Documents 1 and 2 have electrode layers formed by coating both sides of the ion-conductive polymer film with a composition. The composition is produced by dispersing carbon powder in an ion-conductive polymer. Forming the electrode layers with an ion-conductive polymer and carbon powder provides improved productivity and reduced manufacturing cost.
However, polymer actuators in the past using an ionic liquid as described in Patent Documents 1 to 4 are slow to deform (operate) and deform in an irregular manner.
In light of the foregoing, it is desired to provide a polymer actuator which is quick to operate and deforms to a large extent.